text: # Copyright 2016 Donald Stufft and individual contributors
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  from __future__ import absolute_import, division, print_function
  
  import nacl.exceptions as exc
  from nacl._sodium import ffi, lib
  from nacl.exceptions import ensure
  
  
  has_crypto_shorthash_siphashx24 = bool(
      lib.PYNACL_HAS_CRYPTO_SHORTHASH_SIPHASHX24
  )
  
  BYTES = lib.crypto_shorthash_siphash24_bytes()
  KEYBYTES = lib.crypto_shorthash_siphash24_keybytes()
  
  XBYTES = 0
  XKEYBYTES = 0
  
  if has_crypto_shorthash_siphashx24:
      XBYTES = lib.crypto_shorthash_siphashx24_bytes()
      XKEYBYTES = lib.crypto_shorthash_siphashx24_keybytes()
  
  
  def crypto_shorthash_siphash24(data, key):
      """Compute a fast, cryptographic quality, keyed hash of the input data
  
      :param data:
      :type data: bytes
      :param key: len(key) must be equal to
                  :py:data:`.KEYBYTES` (16)
      :type key: bytes
      """
      if len(key) != KEYBYTES:
          raise exc.ValueError(
              "Key length must be exactly {0} bytes".format(KEYBYTES)
          )
      digest = ffi.new("unsigned char[]", BYTES)
      rc = lib.crypto_shorthash_siphash24(digest, data, len(data), key)
  
      ensure(rc == 0, raising=exc.RuntimeError)
      return ffi.buffer(digest, BYTES)[:]
  
  
  def crypto_shorthash_siphashx24(data, key):
      """Compute a fast, cryptographic quality, keyed hash of the input data
  
      :param data:
      :type data: bytes
      :param key: len(key) must be equal to
                  :py:data:`.XKEYBYTES` (16)
      :type key: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_shorthash_siphashx24,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      if len(key) != XKEYBYTES:
          raise exc.ValueError(
              "Key length must be exactly {0} bytes".format(XKEYBYTES)
          )
      digest = ffi.new("unsigned char[]", XBYTES)
      rc = lib.crypto_shorthash_siphashx24(digest, data, len(data), key)
  
      ensure(rc == 0, raising=exc.RuntimeError)
      return ffi.buffer(digest, XBYTES)[:]
  